Wiring The Brain to Aid People With Paralysis

Scientists are reporting progress in their efforts to channel brain waves to power mechanical devices, a development that could someday help paralyzed people regain mobility.

Researchers efforts to overcome paralysis and loss of function caused by spinal cord injuries have monkeys using mind control and paralyzed rats walking again. WSJ's Christina Tsuei reports on research innovations by scientists across the nation.

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A person who suffers a brain-stem or spinal-cord injury because of an accident, stroke or disease can lose the ability to transmit the brain's messages to the rest of the body. Tapping these brain signals, and rerouting them by other means to artificial limbs or other devices, could enable a paralyzed person to perform some everyday functions, from picking up a fork to walking, scientists expect.

With paralysis, "the body you live in has changed. You need to remap" how commands from the brain get to the rest of the body, says Miguel Nicolelis, a neurobiologist and leader of the so-called brain-machine-interface research program at Duke University's school of medicine. Dr. Nicolelis says the program recently received a grant to begin testing on people in 2014 a full-body prosthetic controlled solely by the patient's brain waves.

The Duke researchers have previously trained lab monkeys to move a robotic arm in a separate location and play simple video games. Now, the researchers have begun a more complex set of experiments aimed at teaching monkeys to control with their thoughts a full-body avatar projected on a computer screen. Directing the movements of an entire body is much more difficult than controlling just an arm or leg.

The monkeys are implanted with small electrodes in the brain that record signals from hundreds of neurons. They then wear 3-D movie goggles so they can feel as though they are part of the virtual world.

In one trial, monkeys see their entire avatar on the screen and learn to control it. Once the real monkey appears to realize its thoughts control the avatar, the researchers plan to introduce a second digital monkey in the virtual world to allow them to interact.

In another experiment, monkeys are learning that they are the avatar. Instead of seeing a full-body digital primate, they view the virtual world through the eyes of the avatar. If the monkey looks down, for instance, the avatar on the computer screen will see his own digital feet.

Initially, the monkeys move their real arms and legs, as they watch the avatars performing the same actions. But previous experiments with the monkeys have shown that the monkeys eventually will come to realize they only have to think about moving in order to navigate the avatar, Dr. Nicolelis says.

It can take between two and six months for a monkey to comprehend the abstract idea of controlling an object merely by thinking about it. At that moment, the monkeys stop moving their own bodies and relax and "you see they have got it," Dr. Nicolelis says. People, of course, can simply be told to think about a specific movement, and master the control process fairly quickly, he says.

Unlike moving only limbs, full-body movement is a particular challenge because it involves posture, weight and balance—all necessary to holding the body upright. Moving an entire body also requires extensive information recorded from many neurons in the brain, says Dr. Nicolelis.

Currently the electrodes implanted in the monkeys are able to record up to about 1,000 neurons from above the cortex, the part of the brain that is involved in thinking and memory. This is enough to operate a full-body prosthetic, Dr. Nicolelis says. Still, his team is currently working on technology that will allow the researchers soon to record signals from 5,000 neurons, and eventually from 50,000, he says.

Eventually, the research team plans to move from a virtual monkey on a computer screen to outfitting the primates, and eventually people, with a suit that looks a bit like a metal skeleton attached to the outside of the body.

The idea is to harness the wearer's brain signals and send them wirelessly to sensors located throughout the full-body prosthetic. The Duke researchers are working with other scientists who are developing such a full-body device that may one day allow paralyzed people to walk again.

Jennifer French, who became a quadriplegic after a snowboarding accident more than a decade ago, believes advances in technology can help people like her but is cautious about the prospect of electrodes being implanted in her brain. The 39-year-old retains some upper-arm movement but not fine motor control. In 1999 she had electrodes implanted in her paralyzed legs. These enable her with the push of a button to stand up from her wheelchair, helping to avoid bedsores and muscle spasms from sitting too long in one place.

Ms. French, who heads the Neurotech Network, a nonprofit in Tampa, Fla., that educates the public on technologies available for people with disabilities, says she would carefully weigh the benefits if someone were to present her with the choice of getting a brain implant. "What am I going to gain against the potential risk?" she says.

One request Ms. French has for scientists is to develop a feedback system, so that a prosthetic can send messages back to the brain. For instance, she says it would be helpful if a paralyzed person who is able to stand or walk with the help of technology could also feel the weight of the ground underneath the feet.

Dr. Nicolelis says the Duke team is working on just such a system. He says they hope to implant sensors at points in the full-body prosthetic, such as where the feet touch the ground, that will transmit signals back to the wearer's brain.

Researchers at other academic institutions and in industry have also demonstrated that it is possible for people to use their thoughts to control external devices, such as a cursor on a computer screen and a robotic arm. One such experiment from 2006 was published in the journal Nature.

For some patients, particularly those with little voluntary movement or speech because of a stroke or a disease like ALS, the end goal is to help them do everything that an able-bodied person could do on the computer using a one-button mouse, says Leigh Hochberg, an author of the Nature study and a neuroscientist at Massachusetts General Hospital in Boston. Being able to browse the Web and use speech-detection software could help them improve communication with caregivers and generally feel more connected to the world, he says.

Amputees who already use prosthetic or robotic limbs could see improved devices that allow for better control, researchers say. One day, the artificial limb could provide feedback to the brain so that in reaching for a cup of coffee cup, for instance, sensors in the limb could tell the user whether the liquid inside is hot or cold.

Some forms of electrical and so-called assistive-communication devices are already on the market. These, however, don't work based on brain signals, but require at least some ability to move, such as a finger or a turn of the head. Eye-gaze technology, for instance, allows an individual to stare at letters or words on a screen to communicate meaning.

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